month=int(input("请输入月份："))
year=2020
match  month:  # case后面的值的类型跟month类型保持一致
    case 1:
       print("31天")
    case 3:
        print("31天")
    case 2:
        if year % 4 == 0 and year % 100 != 0 or year % 400 == 0:
            print("这个月是29天")
        else:
            print("这个月是28天")

